1. Field of the Invention
The present invention relates to an imaging device that images a target object mounted on a table by a camera head from above the table.
2. Description of the Related Art
When not in use, the camera head, which is a precision device, in this type of imaging device should be kept as stable as possible when held against the table by an arm. The total height of the device for tilting the support arm toward the table to bring the camera closer to the table is lowered, for example. The way the camera head is held by such an arm can be seen in Japanese Patent Laid-open Gazette No. 2005-23620A, for example.
In the imaging device disclosed in that Patent Citation, even though the arm is assisted by a spring provided at the base of the arm when the arm holding the camera head is pulled up from the table, there is still room for the following improvements in this imaging device.
For example, the cable for the signals obtained by the camera head held by the arm and the cable for supplying power to the camera must be routed into the device chassis, and often into the device table. There is usually enough wiring space inside the and table is used as a place for wiring in order to shorten the length of the cable from the arm to the table. When cable is located in the circumference of rotation between the arm and table, the wiring and spring can interfere with each other, and as such interference has not been taken into sufficient consideration, the cable can become damaged by contact with the spring. The circumference of the arm rotation thus becomes what is referred to as dead space, which is not used to set up wiring or the like.
As the mounted spring is used not only to provide force when pulling up the arm but also to support the incline of the arm, substantial spring force is required. Wider space is thus needed to mount the spring to increase the number and size of the springs, leading to an increase in the number of arm engagement locations and thus the size of the device.
An object of the present invention is thus to overcome the above problems involved in the structure and rotatability of the arm that supports the camera head, so as to make more effective use of the circumference of the arm rotation while assisting the arm rotation, resulting in a more compact device.